Quick Answer
U0138 means: U0138 indicates a communication failure with the Vehicle Control Module.
Can I drive with U0138? Immediate attention is recommended to prevent further damage.
Common Questions
What does U0138 mean and how does it affect my car?
The U0138 code signifies a communication failure with the Vehicle Control Module, which can affect various systems in your vehicle, leading to performance issues such as stalling, reduced fuel efficiency, and problems with anti-lock brakes. If not addressed, it can escalate into more severe engine or electrical issues.
What are the most common causes of U0138 and how much does it cost to fix?
Common causes include faulty wiring (60% likelihood) and a malfunctioning VCM (25% likelihood). Repair costs vary; wiring repairs can range from $100 to $400, while replacing the VCM can cost between $500 and $1,200.
Can I drive my car with U0138 or should I stop immediately?
It is advisable to stop driving your vehicle immediately if you see the U0138 code. Ignoring it can lead to further damage, including potential safety risks if systems like brakes are affected.
How can I diagnose U0138 myself using GeekOBD APP?
To diagnose U0138, use the GeekOBD APP to scan your vehicle for trouble codes. Review the freeze frame data and look for any related codes. Check wiring and connectors visually, and if comfortable, use a multimeter to test connections.
What vehicles are most commonly affected by U0138?
U0138 is frequently seen in vehicles like the 2015-2019 Ford F-150 and the 2016-2018 Chevrolet Silverado, among others. Check for any recalls or technical service bulletins (TSBs) related to these models for additional guidance.
How can I prevent U0138 from happening again?
Regular vehicle maintenance is vital. Inspect wiring and connectors for wear during routine checks, keep your vehicle's software updated, and address any warning lights immediately to reduce the risk of communication failures.
What is U0138?
The diagnostic trouble code (DTC) U0138 indicates that there is a communication issue between the vehicle's control modules, specifically with the Vehicle Control Module (VCM). This code is often triggered when the engine control module (ECM) or transmission control module (TCM) fails to receive or send data to the VCM. In simpler terms, it means that your car's various electronic systems are not talking to each other effectively, which can lead to various performance issues. For instance, you might notice that your vehicle behaves erratically, such as unexpected engine stalling or issues with the anti-lock braking system (ABS). The U0138 code can lead to a host of problems, including poor fuel efficiency, difficulty starting the engine, and in some cases, a complete loss of power. The impact can vary based on the vehicle make and model, but it is particularly notable in popular trucks like the Ford F-150 and Chevrolet Silverado. Timely diagnosis and repair are essential to avoid more severe issues down the line.
System: U - Network (Communication, CAN Bus)
Symptoms
Common symptoms when U0138 is present:
- The check engine light illuminates and remains on, indicating a problem.
- The engine may hesitate or stall unexpectedly during acceleration, causing a potentially dangerous situation.
- Fuel economy may decrease noticeably, with reports of drops by 10-15%, impacting your wallet over time.
- You may experience issues with other systems like ABS or traction control, leading to unpredictable vehicle behavior.
- In some cases, the vehicle may not start at all, leaving you stranded.
Possible Causes
Most common causes of U0138 (ordered by frequency):
- The most common cause of U0138 is faulty wiring or connectors between the VCM and other control modules, with a likelihood of about 60%. Electrical issues can arise from corrosion or wear over time.
- A second potential cause is a malfunctioning Vehicle Control Module itself, which can lead to communication breakdowns. This is less common but can be serious and typically has a 25% likelihood.
- A third cause could be software issues in the vehicle's computer systems. Regular updates and maintenance checks can help prevent these issues.
- Less common but serious causes include a failed engine control module, which can be costly to replace, often requiring professional diagnostics.
- A rare cause might be a complete short circuit in the vehicle's electrical system, which can cause widespread issues and may require extensive repairs.
U0138 Repair Costs
Cost Breakdown by Repair Type
Wiring Repair
Repair or replacement of damaged wiring or connectors can resolve communication issues.
- Total: $100 - $400
- Success rate: 80%
VCM Replacement
If the Vehicle Control Module is faulty, it may need to be replaced with a new or refurbished unit.
- Total: $500 - $1,200
- Success rate: 90%
Diagnostic Service
A professional diagnostic service can help identify the root cause of U0138.
- Total: $80 - $150
- Success rate: 100%
Money-Saving Tips for U0138
- Start with the most common and least expensive repairs first
- Use GeekOBD APP to confirm diagnosis before replacing expensive parts
- Consider preventive maintenance to avoid future occurrences
- Compare prices for OEM vs aftermarket parts based on your needs
- Address the issue promptly to prevent more expensive secondary damage
Diagnostic Steps
Professional U0138 Diagnosis Process
Follow these systematic steps to accurately diagnose U0138. Each step builds on the previous one to ensure accurate diagnosis.
Step 1: Step 1: Start with an initial visual inspection
Step 1: Start with an initial visual inspection. Look for any obvious signs of damage such as frayed wiring or loose connectors. This should take about 5-10 minutes.
Step 2: Step 2: Use the GeekOBD APP to perform an OBD2 scan
Step 2: Use the GeekOBD APP to perform an OBD2 scan. Retrieve all trouble codes and freeze frame data to get a complete picture of the fault context. This process typically takes 10-15 minutes.
Step 3: Step 3: Conduct component testing with a multimeter
Step 3: Conduct component testing with a multimeter. Test the suspected wiring and connectors to ensure they are functioning properly. Expect this to take around 20-30 minutes.
Step 4: Step 4: After performing any repairs, conduct a system function test
Step 4: After performing any repairs, conduct a system function test. Verify that all systems are operational and clear the codes. This should take about 10-15 minutes.
Step 5: Step 5: Finally, perform a road test under various conditions to confirm that the issue has been resolved
Step 5: Finally, perform a road test under various conditions to confirm that the issue has been resolved. This could take an additional 15-20 minutes.
Important Notes
- Always verify the repair with GeekOBD APP after completing diagnostic steps
- Clear codes and test drive to ensure the problem is resolved
- Address underlying causes to prevent code recurrence
Real Repair Case Studies
Case Study 1: Ford F-150 Communication Issue
Vehicle: 2017 Ford F-150, 85,000 miles
Problem: Customer reported check engine light and intermittent stalling.
Diagnosis: Performed OBD2 scan with GeekOBD APP and retrieved U0138. Visual inspection revealed damaged wiring harness.
Solution: Repaired wiring connections and cleared codes.
Cost: $250 (including parts and labor)
Result: Vehicle operated normally post-repair, with no further issues.
Case Study 2: Chevrolet Silverado VCM Replacement
Vehicle: 2016 Chevrolet Silverado, 72,000 miles
Problem: Owner experienced poor acceleration and check engine light.
Diagnosis: Diagnostics showed U0138; further testing indicated a failed VCM.
Solution: Replaced the VCM with a refurbished unit.
Cost: $800 (parts and labor included)
Result: Improved performance and resolved communication issues.